Home About us Contact
|
Home About us Contact | ||
|
|
||
Experimental Units (experimental + unit)
Selected AbstractsQuality of Nursing Diagnoses: Evaluation of an Educational InterventionINTERNATIONAL JOURNAL OF NURSING TERMINOLOGIES AND CLASSIFICATION, Issue 2 2005Jan Florin RN PURPOSE.,To investigate the effects on the quality of nursing diagnostic statements in patient records after education in the nursing process and implementation of new forms for recording. METHODS.,Quasi-experimental design. Randomly selected patient records reviewed before and after intervention from one experimental unit (n = 70) and three control units (n = 70). A scale with 14 characteristics pertaining to nursing diagnoses was developed and used together with the instrument (CAT-CH-ING) for record review. FINDINGS.,Quality of nursing diagnostic statements improved in the experimental unit, whereas no improvement was found in the control units. Serious flaws in the use of the etiology component were found. CONCLUSION.,Nurses must be more concerned with the accuracy and quality of the nursing diagnoses and the etiology component needs to be given special attention. PRACTICE IMPLICATIONS.,Education of RNs in nursing diagnostic statements and peer review using standardized evaluation instruments can be means to further enhance RNs' documentation practice. [source] A Mixed Modelling Approach for Randomized Experiments with Repeated MeasuresJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2004H. P. Piepho Abstract Repeated measurements on the same experimental unit are common in plant research. Due to lack of randomization and the serial ordering of observations on the same unit, such data give rise to correlations, which need to be accounted for in statistical analysis. Mixed modelling provides a flexible framework for this task. The present paper proposes a general method to formulate mixed models for designed experiments with repeated measurements. The approach is exemplified by way of several examples. [source] Root surface roughness following Er:YAG laser irradiation at different radiation energies and working tip angulationsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 7 2002Matthias Folwaczny Abstract Objectives: The determination of roughness of root surfaces following treatment with 2.94 µm Er:YAG laser radiation at different radiation energies and working tip angulations. Materials and methods: The study sample comprised 85 extracted human molars, premolars, canines and incisors (n = 85). The source of laser radiation was an Er:YAG laser device (KAVO-Key II, System Aesculap Meditec) emitting pulsed infrared radiation at a wavelength of 2.94 µm, with a pulse duration of 250 µs, and a pulse repetition rate of 10 pps. The samples were randomly divided into three experimental units, for treatment with a constant amount of 380 laser pulses at a radiation energy of 60 mJ, 100 mJ, and 180 mJ. Each experimental unit was divided into five subgroups of five samples, which were irradiated at a working tip angulations of 15°, 30°, 45°, 60°, and 90°. Five samples were treated mechanically using curettes. Five samples were left untreated as control. The mean (Ra) and maximum (Rmax) surface roughness of each sample was measured using a profilometer. The statistical analysis was undertaken using anova and Scheffé-test at a level of significance of 5% (p < 0.05). Results: Er:YAG laser radiation led to an Ra which ranged from 0.52 µm (± 0.10) to 0.81 µm (± 0.26) and to an Rmax between 3.4 µm (± 0.48) and 9.26 µm (± 3.08). The Ra and Rmax for samples treated with curettes was 0.51 µm (± 0.11) and 5.08 µm (± 4.98), respectively. That for the untreated control samples were 0.53 µm (± 0.15) and 7.07 µm (± 5.48), respectively. Conclusions: The mean and maximum surface roughness of root surfaces following irradiation with Er:YAG laser was not significantly different to that obtained on samples treated with conventional hand instruments or left untreated. Furthermore, the surface roughness does not depend on the radiation energy and the angulation of the working tip. [source] Diel variation in feeding rate and prey composition of herring and mackerel in the southern Gulf of St LawrenceJOURNAL OF FISH BIOLOGY, Issue 5 2003E. Darbyson Diel feeding patterns of herring Clupea harengus and mackerel Scomber scombrus in the southern Gulf of St Lawrence were examined based on samples obtained by midwater trawling between 19 and 26 June 2001. Within 3 h time periods, stomach contents tended to be more similar between fish from the same tow than between fish from different tows. Thus, in contrast to previous diet studies, which have used individual fish stomachs as independent observations, tow was used as the experimental unit in statistical analyses in this study. Diel patterns in stomach fullness were identified using generalized additive models. Two peaks in stomach fullness occurred for herring, one in the morning and the other in the evening. Mackerel showed an increase in feeding intensity throughout the day with a peak in mid-afternoon. The diel changes in stomach contents suggested rapid gastric evacuation rates for both species, especially for herring. The estimate of the instantaneous evacuation rate for herring was twice that for mackerel. Calanus copepods (mainly C. hyperboreus), fishes (mainly capelin Mallotus villosus) and euphausiids were the main prey found in the stomachs of both species. Calanus copepods dominated the diet of herring regardless of time period. They also dominated the diet of mackerel during the late afternoon, evening and night while fishes and euphausiids were dominant during the morning and early afternoon. These diel patterns emphasize the need for sampling throughout the day and night in order to estimate ration and diet composition for bioenergetic and ecosystem models. [source] Investigations on the digestibility and metabolizability of the major nutrients and energy of maize leaves and barnyard grass in grass carp (Ctenopharyngodon idella)AQUACULTURE NUTRITION, Issue 3 2010E.B. DONGMEZA Abstract In the uplands of northern Vietnam, culture of grass carp contributes significantly to income and household food security of Black Thai farmers. Maize is one of the most important upland crops and barnyard grass is the most important weed in the paddy rice fields. Thus, these are frequently used by small-scale fish farmers as fish feed. An 8-week feeding trial was conducted simultaneously in a recirculation and in a respirometric system to determine the digestibility and metabolizability of the nutrients of maize leaves and barnyard grass, to assess their crude protein, lipid and energy conversion and to estimate the energy allocation in grass carp. The following diets were used: diet ,A' (reference diet) containing 39% crude protein with 19.8 MJ kg,1 gross energy; diets ,B', ,C' and ,D', which contained the same amount of the reference diet as the control diet, supplemented with a known amount of dried barnyard grass, dried maize leaves or fresh maize leaves, respectively. Five fish were assigned to each treatment in each experimental unit. Reference and test diets were fed to fish and faecal samples were collected and the oxygen consumption was measured in order to set up an energy budget of the fish over the whole experimental period. The weekly development of the body weight was recorded. The body weight gain of the fish fed diet D was significantly higher than that of the group fed diet A, which also in turn was significantly higher than that of fish fed diet B or C. The apparent digestibility coefficients (ADC) of nutrients and gross energy for the different experimental diets in fish kept in the aquaria were, for diets A, B, C and D respectively, 94.1%, 60.9%, 70.5% and 84.7% for protein, 91.3%, 60.7%, 76.8% and 71.8% for lipid; 95.9%, 44.5%, 60.6% and 69.1% for gross energy. The partial ADC of plant leaf ingredients were determined and barnyard grass and dried maize leaves were found to be not only poorly digestible but having negative impact on the digestibility of the reference diet, while fresh maize leaves were well digested. The results of the present study indicated that fresh maize leaves have a good potential to be used as supplement in diets for grass carp. [source] The effect of protein levels on growth, postprandial excretion and tryptic activity of juvenile mullet Mugil platanus (Günther)AQUACULTURE RESEARCH, Issue 4 2010Cristina V A De Carvalho Abstract The objective of the present work was to determine the optimum dietary protein level for juvenile mullets. Five isocaloric diets were formulated to contain increasing levels (300, 350, 400, 450 and 500 g kg,1) of crude protein (CP) corresponding to 18.7 MJ metabolizable energy kg,1. All diets were tested in triplicate. Each experimental unit was composed of a 50 L tank with 50 juveniles (mean ± SE initial weight and length equal to 1.17 ± 0.02 g and 4.34 ± 0.03 cm respectively). Diets were offered five times a day until apparent satiation for 35 days. No significant difference (P>0.05) was observed in survival rate, feed efficiency and body composition between treatments. However, weight gain, feed consumption and specific growth rate were higher in fish fed the 350 g kg,1 CP level than those fed the highest protein content diet (500 g kg,1 CP). The amount of postprandial ammonia excreted by mullet was linearly related to protein intake. Intestinal tryptic activity was inversely proportional to the percentage of dietary CP. It is likely that diets containing <350 g kg,1 CP will be needed for on-growing mullet, especially when reared in ponds with abundant natural food. [source] Distillation Tower with Distributed Control Strategy: Feed Temperature LoadsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2007C. Marangoni Abstract Distillation towers require control systems adjusted to rapidly reject loads. Temperature control of these units is normally carried out at the bottom and top of the column, increasing the tower response time. In this paper, a change in this temperature control configuration is proposed through the introduction of heating points distributed among the trays throughout the column. The proposed strategy was tested in an experimental unit with an ethanol-water mixture applying a conventional approach (control at bottom and top only) and the proposed distributed configuration (bottom, top and tower trays) with feed temperature disturbance. The results showed a significant reduction in the time required for the column to stabilize after the load introduction, compared with the conventional approach, making faster dynamics possible. [source] Temporal changes in replicated experimental stream fish assemblages: predictable or not?FRESHWATER BIOLOGY, Issue 9 2006WILLIAMJ. Summary 1.,Natural aquatic communities or habitats cannot be fully replicated in the wild, so little is known about how initially identical communities might change over time, or the extent to which observed changes in community structure are caused by internal factors (such as interspecific interactions or traits of individual species) versus factors external to the local community (such as abiotic disturbances or invasions of new species). 2.,We quantified changes in seven initially identical fish assemblages, in habitats that were as similar as possible, in seminatural artificial streams in a 388-day trial (May 1998 to May 1999), and compared the change to that in fish assemblages in small pools of a natural stream during a year. The experimental design excluded floods, droughts, immigration or emigration. The experimental fish communities diverged significantly in composition and exhibited dissimilar trajectories in multivariate species space. Divergence among the assemblages increased from May through August, but not thereafter. 3.,Differences among the experimental assemblages were influenced by differences that developed during the year in algae cover and in potential predation (due to differential survival of sunfish among units). 4.,In the natural stream, fish assemblages in small pools changed more than those in the experimental units, suggesting that in natural assemblages external factors exacerbated temporal variation. 5.,Our finding that initially identical assemblages, isolated from most external factors, would diverge in the structure of fish assemblages over time suggests a lack of strong internal, deterministic controls in the assemblages, and that idiosyncratic or stochastic components (chance encounters among species; vagaries in changes in the local habitat) even within habitat patches can play an important role in assemblage structure in natural systems. [source] Effect of temperature and host stage on performance of Aphelinus varipes Förster (Hym., Aphelinidae) parasitizing the cotton aphid, Aphis gossypii Glover (Hom., Aphididae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 10 2002O. Röhne Development time, mummification, pupal mortality, host feeding and sex ratio of a Norwegian strain of Aphelinus varipes Förster parasitizing the cotton aphid, Aphis gossypii Glover were studied at 20, 25 and 30°C in controlled climate cabinets. Petri dishes with cucumber (Cucumis sativus L) leaves on agar were used as experimental units. Cotton aphids in different larval instars and as adults, reared at the three different temperatures, were presented to A. varipes in a `no-choice' situation for 6 h. These presentations were done at 25°C in each experiment to avoid an influence of temperature on parasitization rate. More first instar aphids were parasitized than third and fourth instars among the aphids reared at 20°C. Pupal mortality of the parasitoid was not influenced by temperature. It was lower in aphids parasitized as adults than in aphids parasitized in second instar. The sex ratio of A. varipes was female-biased, and varied between 92% females developed from aphids reared at 25°C and 70% from aphids reared at 20°C. The sex ratio was not significantly influenced by host stage. The development time of A. varipes ranged from 17.5 days at 20°C to 9.8 days at 30°C. [source] Influence of storage regime prior to abrasion on surface topography of restorative materialsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2003Cecilia Pedroso Turssi Abstract This investigation was carried out to evaluate the effect of storage conditions prior to brushing simulation on surface texture of restorative materials. One resin-modified glass ionomer (Fuji II LC Improved/GC Corp.), one polyacid-modified composite resin (Dyract AP/Denstply), one microfill composite (Durafill VS/Kulzer), and one hybrid (Filtek,Z250/3M) composite were tested. Forty-five standardized cylindrical specimens of each material were made and randomly divided into three groups according to their subsequent storage conditions: distilled deionized water, artificial saliva, or pH-cycling regime. After 24 h, the experimental units were finished and polished and the surface roughness was measured to obtain Ra baseline values (Bv). Samples were subjected to their assigned storage regime and brushed afterwards. By the end of 10 repetitions of this protocol, final surface roughness readings (Fv) were taken. The analysis of covariance (, = 0.05), considering the covariate Bv showed a significant interaction between restorative material and storage condition (pvalue = 0.0002). Tukey's test revealed that the pH-cycling model provided a significantly lower surface roughness for Fuji II LC and Dyract AP than did the other media. For both composites no significant difference among storage regimes was detected. Under a condition simulating dynamic variation in pH prior to abrasion, the resultant surface texture may be either smoothed down or unchanged, depending on the restorative material, when compared to the effect provided by artificial saliva and distilled deionized water. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 65B: 227,232, 2003 [source] Root surface roughness following Er:YAG laser irradiation at different radiation energies and working tip angulationsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 7 2002Matthias Folwaczny Abstract Objectives: The determination of roughness of root surfaces following treatment with 2.94 µm Er:YAG laser radiation at different radiation energies and working tip angulations. Materials and methods: The study sample comprised 85 extracted human molars, premolars, canines and incisors (n = 85). The source of laser radiation was an Er:YAG laser device (KAVO-Key II, System Aesculap Meditec) emitting pulsed infrared radiation at a wavelength of 2.94 µm, with a pulse duration of 250 µs, and a pulse repetition rate of 10 pps. The samples were randomly divided into three experimental units, for treatment with a constant amount of 380 laser pulses at a radiation energy of 60 mJ, 100 mJ, and 180 mJ. Each experimental unit was divided into five subgroups of five samples, which were irradiated at a working tip angulations of 15°, 30°, 45°, 60°, and 90°. Five samples were treated mechanically using curettes. Five samples were left untreated as control. The mean (Ra) and maximum (Rmax) surface roughness of each sample was measured using a profilometer. The statistical analysis was undertaken using anova and Scheffé-test at a level of significance of 5% (p < 0.05). Results: Er:YAG laser radiation led to an Ra which ranged from 0.52 µm (± 0.10) to 0.81 µm (± 0.26) and to an Rmax between 3.4 µm (± 0.48) and 9.26 µm (± 3.08). The Ra and Rmax for samples treated with curettes was 0.51 µm (± 0.11) and 5.08 µm (± 4.98), respectively. That for the untreated control samples were 0.53 µm (± 0.15) and 7.07 µm (± 5.48), respectively. Conclusions: The mean and maximum surface roughness of root surfaces following irradiation with Er:YAG laser was not significantly different to that obtained on samples treated with conventional hand instruments or left untreated. Furthermore, the surface roughness does not depend on the radiation energy and the angulation of the working tip. [source] On the analysis of long-term experimentsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2007Thomas M. Loughin Summary., Long-term experiments are commonly used tools in agronomy, soil science and other disciplines for comparing the effects of different treatment regimes over an extended length of time. Periodic measurements, typically annual, are taken on experimental units and are often analysed by using customary tools and models for repeated measures. These models contain nothing that accounts for the random environmental variations that typically affect all experimental units simultaneously and can alter treatment effects. This added variability can dominate that from all other sources and can adversely influence the results of a statistical analysis and interfere with its interpretation. The effect that this has on the standard repeated measures analysis is quantified by using an alternative model that allows for random variations over time. This model, however, is not useful for analysis because the random effects are confounded with fixed effects that are already in the repeated measures model. Possible solutions are reviewed and recommendations are made for improving statistical analysis and interpretation in the presence of these extra random variations. [source] Bayesian clustering and product partition modelsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 2 2003Fernando A. Quintana Summary. We present a decision theoretic formulation of product partition models (PPMs) that allows a formal treatment of different decision problems such as estimation or hypothesis testing and clustering methods simultaneously. A key observation in our construction is the fact that PPMs can be formulated in the context of model selection. The underlying partition structure in these models is closely related to that arising in connection with Dirichlet processes. This allows a straightforward adaptation of some computational strategies,originally devised for nonparametric Bayesian problems,to our framework. The resulting algorithms are more flexible than other competing alternatives that are used for problems involving PPMs. We propose an algorithm that yields Bayes estimates of the quantities of interest and the groups of experimental units. We explore the application of our methods to the detection of outliers in normal and Student t regression models, with clustering structure equivalent to that induced by a Dirichlet process prior. We also discuss the sensitivity of the results considering different prior distributions for the partitions. [source] Stability of ecosystem properties in response to above-ground functional group richness and compositionOIKOS, Issue 1 2000David A. Wardle While there has been a rapidly increasing research effort focused on understanding whether and how composition and richness of species and functional groups may determine ecosystem properties, much remains unknown about how these community attributes affect the dynamic properties of ecosystems. We conducted an experiment in 540 mini-ecosystems in glasshouse conditions, using an experimental design previously shown to be appropriate for testing for functional group richness and composition effects in ecosystems. Artificial communities representing 12 different above-ground community structures were assembled. These included treatments consisting of monoculture and two- and four-species mixtures from a pool of four plant species; each plant species represented a different functional group. Additional treatments included two herbivore species, either singly or in mixture, and with or without top predators. These experimental units were then either subjected to an experimentally imposed disturbance (drought) for 40 d or left undisturbed. Community composition and drought both had important effects on plant productivity and biomass, and on several below-ground chemical and biological properties, including those linked to the functioning of the decomposer subsystem. Many of these compositional effects were due to effects both of plant and of herbivore species. Plant functional group richness also exerted positive effects on plant biomass and productivity, but not on any of the below-ground properties. Above-ground composition also had important effects on the response of below-ground properties to drought and thus influenced ecosystem stability (resistance); effects of composition on drought resistance of above-ground plant response variables and soil chemical properties were weaker and less consistent. Despite the positive effects of plant functional group richness on some ecosystem properties, there was no effect of richness on the resistance of any of the ecosystem properties we considered. Although herbivores had detectable effects on the resistance of some ecosystem properties, there were no effects of the mixed herbivore species treatment on resistance relative to the single species herbivore treatments. Increasing above-ground food chain length from zero to three trophic levels did not have any consistent effect on the stability of ecosystem properties. There was no evidence of either above-ground composition or functional group richness affecting the recovery rate of ecosystem properties from drought and hence ecosystem resilience. Our data collectively point to the role of composition (identity of functional group), but not functional group richness, in determining the stability (resistance to disturbance) of ecosystem properties, and indicates that the nature of the above-ground community can be an important determinant of the consistency of delivery of ecosystem services. [source] Effect of a postfire environment on the establishment of Prosopis caldenia seedlings in central semiarid ArgentinaAUSTRAL ECOLOGY, Issue 5 2007ANA E. De VILLALOBOS Abstract The objective of this work was to evaluate postfire environmental effects on the emergence, survival and growth of Prosopis caldenia seedlings in relation to different controlled fire frequencies, seed scarification methods, and planting site. Seedling emergence was significantly higher in experimental units exposed twice and three times to controlled fire than in unburned experimental units. The highest average seedling survival was recorded with triple exposure to controlled fires. Emergence, survival and growth of seedlings from seeds exposed to acid scarification and 600°C for 5 min were higher in the burned experimental units than in the unburned ones. In the former, seedling survival was higher beneath a P. caldenia canopy than in an adjacent open site, though seedling emergence was similar in both planting sites. Our results suggest that postfire conditions characterized by a reduction in the vegetative cover and competition interference and an increase in soil temperatures and nutrients levels (e.g. nitrogen and phosphorus) may facilitate the establishment of P. caldenia seedlings in the Caldenal. [source] Some contributions to the analysis of multivariate dataBIOMETRICAL JOURNAL, Issue 2 2009Arne C. Bathke Abstract In this paper, we provide an overview of recently developed methods for the analysis of multivariate data that do not necessarily emanate from a normal universe. Multivariate data occur naturally in the life sciences and in other research fields. When drawing inference, it is generally recommended to take the multivariate nature of the data into account, and not merely analyze each variable separately. Furthermore, it is often of major interest to select an appropriate set of important variables. We present contributions in three different, but closely related, research areas: first, a general approach to the comparison of mean vectors, which allows for profile analysis and tests of dimensionality; second, non-parametric and parametric methods for the comparison of independent samples of multivariate observations; and third, methods for the situation where the experimental units are observed repeatedly, for example, over time, and the main focus is on analyzing different time profiles when the number p of repeated observations per subject is larger than the number n of subjects. [source] | |||||||||||||||||||